[AArch64] Add an endian_lane_rtx helper routine

[AArch64] Add an endian_lane_rtx helper routine

Later patches turn the number of vector units into a poly_int.
We deliberately don't support applying GEN_INT to those (except
in target code that doesn't distinguish between poly_ints and normal
constants); gen_int_mode needs to be used instead.

This patch therefore replaces instances of:

  GEN_INT (ENDIAN_LANE_N (builtin_mode, INTVAL (op[opc])))

with uses of a new endian_lane_rtx function.

2017-11-06  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* config/aarch64/aarch64-protos.h (aarch64_endian_lane_rtx): Declare.
	* config/aarch64/aarch64.c (aarch64_endian_lane_rtx): New function.
	* config/aarch64/aarch64.h (ENDIAN_LANE_N): Take the number
	of units rather than the mode.
	* config/aarch64/iterators.md (nunits): New mode attribute.
	* config/aarch64/aarch64-builtins.c (aarch64_simd_expand_args):
	Use aarch64_endian_lane_rtx instead of GEN_INT (ENDIAN_LANE_N ...).
	* config/aarch64/aarch64-simd.md (aarch64_dup_lane<mode>)
	(aarch64_dup_lane_<vswap_width_name><mode>, *aarch64_mul3_elt<mode>)
	(*aarch64_mul3_elt_<vswap_width_name><mode>): Likewise.
	(*aarch64_mul3_elt_to_64v2df, *aarch64_mla_elt<mode>): Likewise.
	(*aarch64_mla_elt_<vswap_width_name><mode>, *aarch64_mls_elt<mode>)
	(*aarch64_mls_elt_<vswap_width_name><mode>, *aarch64_fma4_elt<mode>)
	(*aarch64_fma4_elt_<vswap_width_name><mode>):: Likewise.
	(*aarch64_fma4_elt_to_64v2df, *aarch64_fnma4_elt<mode>): Likewise.
	(*aarch64_fnma4_elt_<vswap_width_name><mode>): Likewise.
	(*aarch64_fnma4_elt_to_64v2df, reduc_plus_scal_<mode>): Likewise.
	(reduc_plus_scal_v4sf, reduc_<maxmin_uns>_scal_<mode>): Likewise.
	(reduc_<maxmin_uns>_scal_<mode>): Likewise.
	(*aarch64_get_lane_extend<GPI:mode><VDQQH:mode>): Likewise.
	(*aarch64_get_lane_zero_extendsi<mode>): Likewise.
	(aarch64_get_lane<mode>, *aarch64_mulx_elt_<vswap_width_name><mode>)
	(*aarch64_mulx_elt<mode>, *aarch64_vgetfmulx<mode>): Likewise.
	(aarch64_sq<r>dmulh_lane<mode>, aarch64_sq<r>dmulh_laneq<mode>)
	(aarch64_sqrdml<SQRDMLH_AS:rdma_as>h_lane<mode>): Likewise.
	(aarch64_sqrdml<SQRDMLH_AS:rdma_as>h_laneq<mode>): Likewise.
	(aarch64_sqdml<SBINQOPS:as>l_lane<mode>): Likewise.
	(aarch64_sqdml<SBINQOPS:as>l_laneq<mode>): Likewise.
	(aarch64_sqdml<SBINQOPS:as>l2_lane<mode>_internal): Likewise.
	(aarch64_sqdml<SBINQOPS:as>l2_laneq<mode>_internal): Likewise.
	(aarch64_sqdmull_lane<mode>, aarch64_sqdmull_laneq<mode>): Likewise.
	(aarch64_sqdmull2_lane<mode>_internal): Likewise.
	(aarch64_sqdmull2_laneq<mode>_internal): Likewise.
	(aarch64_vec_load_lanesoi_lane<mode>): Likewise.
	(aarch64_vec_store_lanesoi_lane<mode>): Likewise.
	(aarch64_vec_load_lanesci_lane<mode>): Likewise.
	(aarch64_vec_store_lanesci_lane<mode>): Likewise.
	(aarch64_vec_load_lanesxi_lane<mode>): Likewise.
	(aarch64_vec_store_lanesxi_lane<mode>): Likewise.
	(aarch64_simd_vec_set<mode>): Update use of ENDIAN_LANE_N.
	(aarch64_simd_vec_setv2di): Likewise.

Reviewed-by: James Greenhalgh <james.greenhalgh@arm.com>
Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r254466